Relief valve construction



March 11, 1952 2,588,527

T. H. HOLMES RELI EF VALVE CONSTRUCTION Filed April 13, 1944 I l7 3o X n INVENTOR.

YR'ENT HH LMES BY f I v a 1 Q AGENT Patented Mar. 11, 1952 RELIEF VALVE CONSTRUCTION Trent Hr Holmes, Middletown, Conn., assignor by mesne assignments to Niles-Bement-Pond Company, Hartford, Conn.,. a corporation of New Jersey Application April 13, 1944, Serial No. 530,872

6 Claims. i

This invention relates to valves and particularly to a pressure relief valve adapted primarily for fuel pumps for internal combustion engines.

An object of the. invention is to improve the pressure applying device for the relief valve spring so that this valve may have an extremely slight movement away from its seat against the pressure of a light spring, this opening being sufficient to enable gases trapped Within the pump to escape during the normal operation of the pump but. restricting passage past the valve of any liquid such as gasoline or other liquid fuel until a predetermined pressure has been built up within the pump. 3

Another object of the invention is tov provide means for retracting the end of the relief valve spring adjacent the relief valve so that the relief valve may be opened slightly against the pressure of a light spring prior to the pressure of the main relief valve spring. being applied against further opening movement of the valve.

And finally it is an object'of the invention to provide adjusting means for positioning the main pressure applying spring relatively to the valve so that the valve may have an adjustable slight relatively free movement prior to its engagement with and compression of the main pressure applying spring, the pressure of this spring being regulated in the usual manner.

With the above and other objects in view the invention includes the featuresjof construction and operation set forth in the following specification and illustratedin the accompanying drawing.

In the accompanying drawing annexed heretoand forming a part. of this specification, I have shown the invention embodied in a standard form of fuel pump for aircraft. engines, but it will be understood that the invention can be otherwise embodied and that the drawing is not to be construed as defining or limiting the, scope of the invention, the claims appended to this specification being relied upon for that purpose.

In the drawing the figure shows a central longitudinal section, in elevation of a portion of a standard fuel pump, a relief valve and controlling mechanism therefor forming the present invention being shown in operative relation thereto.

In the above-mentioned drawing there has been shown but one embodiment of the invention which is now deemed preferable, but it is to be understood that changes and modifications may be made within the scope of the a pended claims without departing from the spirit of the invention.

Briefly and in its'preferred' aspect, the invention may include the following principal parts: First, a pump, that shown in the accompanying figure being a rotating vane type fuel pump for aircraft engines, a part only of the rotating member and pump casing beingshown; second, a pressure relief valve for said pump normally forced by spring pressure toward its seat; third, means to regulate the pressure exerted by said spring to force the valve towardits closed position; fourth, means to restrict the extended position of the spring adjacent the valve; and fifth, a supplemental light spring engaging and normally forcing the valve into its closed position.

Referring more in detail to the figure of the drawing, there is shown a portion of a fuel pump casing 10 of standard or. conventional rotating vane type. This pump may, as is usual, have a pressure relief valve l l of usual construction normally forced toward its seat I! by a spring l3 and being guided by engagement of short cylindrical piston portions l4 and Ma forming parts of the relief valve and slidable within. suitably bored. portions of the valve casing I9. Also, if desired, the valve ll may have a reverse acting relief valve [5 engaging the lower surface of the pressure relief valve II and normally spring pressed toward its closed position as shown. As this reverse acting relief valve forms no part of the present invention, no further description is thought to be necessary.

Above the upper cylindrical guiding portion. Id of the relief valve H is. a flexible diaphragm l6 and on either side of this diaphragm are dished plates I! and It. The lower plate I! directly engages the upper surface of the relief valve. The periphery of the diaphragm is clamped between surfaces of the valve casing l9-and the valve'bonnet 20 so that limited movements of the value 1 I, the plates I! and I8 and the central portion of the diaphragm l6 are permitted. The diaphragm [3 may be, as usual, of rubber or composition having some of the qualities of rubber permitting flexure when the valve is moved from open to closed position while maintaining a pressure tight joint. Above the upper plate I8 is the main relief pressure applying spring I 3. The lower end of this. spring [3 fits within the flange of a cap mem-- ber 22, the edges of which are closely adjacent or may bear against the upper diaphragm plate I 8; The. upper end of the pressure applying spring I 3 may be adjusted by rotation of an adjusting screw 23 which may be retained in any adjusted position by a flange formed thereon being clamped by a collar 24 threaded uponv the outer or upper end of the valve bonnet 20. By rotation of the threaded member 23 the position of the upper end of the spring I3 may be widely varied to vary the pressure at which the relief valve may open. The upper end of spring I3 bears against a retainer 32 which threadedly engages the screw 23. The retainer 32 is held against rotation by lug 33 which engages in slot 34 in bonnet so that rotation of member 23 produces vertical movement of retainer 32, thereby varying the loading of spring I3.

To determine and limit the extended position of the lower end of the pressure applying spring I3 so that the valve II may have free but extremely limited movement from its seat prior to compression of the spring I3, the cap member 22 against which the lower end of the spring bears is held in any adjusted position by a vertically disposed screw 25. The head of the screw 25 at its lower end engages against the under side of the bearing or cap member 22. The cap member 22 and spring I3 can therefore move upward but their lowermost position is governed by the vertical adjustment of the cap member 22 which is controlled by the position of the head of screw 25. As will be seen in the figure, the rod or screw 25 extends centrally through the nut 23. To raise and lower this threaded rod 25 to vary the position of the cap member 22 to limit the position of the lower end of spring I3, the rod 25 at its upper end has threaded thereon a nut 26 centrally disposed above the nut 23 for adjusting the pressure of spring I3. Preferably there is a spring washer 21 between these nuts 23 and 26 and a second spring washer 28 above the nut 26 and below a cap nut 29 extending over the upper end' of the threaded, rod 25. Disposed between the cap member 22 and the upper diaphragm plate I8 is a light spring 30. With the cap member 22 in its lowermost position as shown in the figure, the valve I I is held in contact with its seat by the spring 30.

In adjusting this relief valve I I the pressure of spring I3 at which the relief valve may open in the usual manner is regulated by adjustment of the threaded nut 23 by means of which the upper end of the spring I3 is raised or lowered. While this adjustment is being efiected the head of threaded rod 25 is in a position low enough to permit the full pressure of the spring I3 to act against the relief valve II and hold it firmly against its seat I2. slightly by rotation of its nut 26 untihthe cap or bearing member 22 for the lower end of the spring I3 just releases its pressure from the upper diaphragm plate I8 to permit vapors entrapped within the discharge side of the pump to escape past the relief valve I I. The opening, however, will not be sufficient to permit passage of any liquid past the valve I I until the pressure retaining the valve II against its seat I2 is overcome and the relief valve II opened against the pressure of this spring I3. During normal operation of the pump with the valve lI held toward its seat I2 by spring I3 a light spring 30 holds the valve II tightly closed but permits slight movement upward of the valve II without compression of spring I3 and during normal operation of the pump. As soon as a predetermined pressure within the discharge side of the pump is reached, the spring I3 is compressed in the usual manner and the valve II opens;

What I claim is:

1.- Relief valve mechanism comprising a casing having a valve seat therein, a valve means within said casing cooperating with said seat, a first spring retainer, means operable from the The rod 25 is then raised exterior of said casing for adjusting the position of said retainer with respect to said casing, means for locking said retainer in any adjusted position, a second spring retainer, an abutting connection between said second retainer and said valve means, a first spring held in compression between said retainers and effective to bias said second retainer in a direction to operatively engage said valve means and move it toward closed position, a second spring retained between said second retainer and said valve means and biasing said valve means toward closed position, means for limiting the movement of said second retainer toward said valve means so that when said valve means is in a range of positions near its closed position only said second spring is effective to bias said valve means, means operable from the exterior of said casing independently of the adjustment of said first retainer adjusting means, for adjusting the position of said limiting means, and means for locking said limiting means in any adjusted position.

2. Relief valve mechanism comprising a casing having a valve seat therein, a valve within said casing cooperating with said seat, a plurality of pistons on opposite sides of said valve, reciprocable in bores in said casing, for guiding said valve, a spring for biasing said valve toward said seat, stop means for limiting the movement of said spring toward said valve seat to permit said valve to move a predetermined distance from said seat without opposition by said spring, means movable from the exterior of said casing for adjusting the loading of said spring, and means movable from the exterior of said casing independently of the adjustment of the first movable means for adjusting the position of said stop means to vary said distance.

3. Relief valve mechanism comprising a casing having a valve seat therein, a valve within said casing cooperating with said seat, said casing having a bore aligned with said valve and extending thru said casing to the exterior thereof; a spring located in said bore for biasing said valve toward said seat; a retainer for the outer end of said spring slidable longitudinally in said bore but non-rotatably mounted therein; an adjustment member in said bore having a nut portion outside said casing to facilitate rotation thereof, a, flange portion adjacent said nut portion of greater diameter than said bore so that the edge of said flange portion engages said casing around said bore, and a portion projecting into. said bore and threadedly engaging said retainer' so that rotation of said adjustment member causes longitudinal movement of said retainer; a lock nut threadedly engaging said .casing around said adjustment member and having a portion overlying said flange portion so as to engage said flange portion and lock said member against rotation when said nut is tightened;

said adjustment member having a bore extending.

longitudinally thru its center; a retainer for the inner end of said spring having a central aperture; a stop member having a stem portion extending thru said bore in said adjustment member and thru said aperture, an enlarged head portion engaging the inner face of said inner retainer to limit the inward movement thereof soas to permit said valve to move a predetermined distance from said seat without opposition by said spring, and a threaded portion extending outwardly of said casing beyond said adjustment member; and nut means on said threaded portion of said stop member for adjusting the I position of said inner retainer and thereby varying said distance.

4. A relief valve mechanism according to claim 2 including a second spring between said stop and said valve, the loading of said second spring 'being relatively much lighter than the loading of the first spring, so as to permit said valve to open only enough to pass vapors thru said valve, but not enough to pass liquids therethru.

5. Relief valve mechanism according to claim 1, including a flexible sealing diaphragm attached to said valve and said casing.

6. Relief valve mechanism according to claim 2, including a flexible sealing diaphragm attached to said valve and said casing.

TRENT H. HOLMES.

REFERENCES CITED UNITED STATES PATENTS Numl er Name Date Lohbiller Nov. 17, 1891 Kraut Feb. 27, 1917 Hofiman Nov. 27, 1923 Erbach Dec. 3, 1929 Clapp July 22, 1930 Deming Aug. 26, 1930 Ford Dec. 18, 1934 Wilkins Mar. 16, 1937 Bennett Oct. 3, 1939 Moore Oct. 7, 1941 Curtis Jan. 6, 1942 Friedell Feb. 15, 1944 Caserta July 11, 1944 

